There's no substitute for crappy pop science and "it doesn't make sense to me so it can't be true" when talking to someone with a preferred notion they are trying like hell to support over and over again. OF COURSE they know more about the intricacies of this than all of those so-called liberal "climate scientists".
I love the "Earth goes in cycles argument". It's just like answering every undesirable scientific fact with "God did it". You can't really say anything about it because, well, the Earth has had warming and cooling cycles.
What deniers can't explain is what exactly is causing the Earth's current trend towards a warming cycle now. While science has explained many of the warming and cooling cycles in the Earth's past, there are no factors (other than man) that explain what has been happening over the past 30 years or so. Past factors include solar variations, volcanoes and Milankovitch cycles (changes in the Earth's orbit). None of these things are in play now. What they willfully ignore is that CO2, a greenhouse gas, is 35% more prevalent in the atmosphere than it was 30 years ago.
Greenhouse gasses cause more heat from the sun to be retained. More retained heat causes higher temperatures over time. Higher temperatures cause the freaking glaciers to melt, the seas to rise, the oceans to desalinate and the Earth to warm. There is an increase in CO2 that is indisputable. We are causing it and your denial does not make it otherwise.
But as always, whatever makes you feel better...